Method of making thermosensitive resistors



June 7, 1932. o, GRONDAHL 1,862,014

METHOD OF MAKING THERMOSENSITIVE RESISTORS Original Filed July 8, 1923INVENTOR. 1,.0. Grondahl,

Patented June 7, 1932 UNITED STATES PATENT OFFICE LABS O. GRONDAHL, OFPITTSBURGH, PENNSYLVANIA, ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY,OF SWISSVALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

METHOD OF MAKING THERMOSENSITIVE RESISTORS Original application filedJanuary 8, 1923, Serial No. 611,286. Yatent No. 1,741,231, datedDecember 31, 1929. Divided and this application filed April 25, 1929.Serial No. 357,993.

My invention relates to electrical translating apparatus of thethermosensitive type, and has for an object the provision of novel andimproved methods for manufacturing devices of this type.

The present application is a division of my copending application,Serial No. 611,286, filed January 8, 1923, for electrical translatingapparatus now Patent No. 1,741,231, De-

cember 31, 1929.

ll will describe several methods embodying my invention, and will thenpoint out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a view showing one form ofthermos-ensltive device which may be manufactured in accordance withmethods embodying my invention. Fig. 2 is a View showing a modificationof the device shown in Fig. 1 and also capable of being manufactured bymethods embodying my invention.

Similar reference characters refer to similar parts in both of theviews.

Referring first to Fig. 1, the device, which '25 is designated as awhole by the reference character R comprises a glass bulb '4', one endof which is provided with a plugS having contacts or terminals 9 and 12,and the other end of which is provided with a similar plug 8 havingcontacts or terminals 9 and 12.

Located within the bulb 7 are a heating element H and two electrodes 10and 11, all of which are in the form of wires. The electrodes may, forexamples, be of copper, or of nickel plated with copper. Theseelectrodes are first twisted together or intertwined to form two helicalconductors with the turns of one alternating with the turns of theother, and the heating element H is then twisted around the electrodes.The whole unit is then heated in a furnace to transform the coppersurface of each electrode into copper oxide which is a thermosensitivesubstance, so that each turn of each electrode is separated from theadjacent turns of the other electrode and from the heating element by acoating of this substance. Or to express the same thing in a differentway the intertwined electrodes are embedded in the thermosensitivesubstance. The device shown in Fig. 1 may be so designed as to carryrelatively heavy currents.

The two terminals of the heating element H are connected with the twocontacts 9 and 12, respectively, of the terminal plug 8. The twoelectrodes 10 and 11 are connected with the two terminals 9 and 12respectively, of the plug 8.

Referring now to Fig. 2, the device, which is here designated as a wholeby the reference character R comprises a glass bulb 7 provided with twoplugs 8 and8, as in the preceding view. ln Fig. 2, however, theelectrodes, which are here designated 10 and 11", are in the form ofwires or strips, which are placed side by side, and the heating elementH is then wrapped around these electrodes. The electrodes may be ofcopper, or they may be of other suitable metal such as nickel, platedwith copper. In either case, after the electrodes and the'heatingelement are assembled, the unit is baked in a furnace to convert thecopper surfaces of the electrodes into copper oxide, so that theseelectrodes are separated from each other and from the heating element Hby a thermosensitive substance. After the baking is finished, the partsare mounted'in the tube 7 gr d cionnected with the plug contacts as inAlthough T have herein described only a few methods embodying myinvention, it is understood that various changes and modifications maybe made therein within the scope of the appended claims withoutdeparting from the spirit and scope of my invention.

- Havingthus described my invention, what I claim is:

1. The method of constructing a thermosensitive device, which consistsin copper plating two metallic electrodes, twisting them together, andthen heating them to form a layer of thermosensitive substance betweenthe electrodes.

2. The method of constructing a thermosensitive device, which consistsin twisting two copper wires together so that the turns of one wirealternate with the turns of the other, and then heating them to form alayer of copper oxide'between the wires.

3. The method of constructing a thermosensitive device, which consistsin copper plating two metallic electrodes, twisting them together sothat the turns of one alternate with the turns of the other, and thenheating them to form a layer of copper oxide between the wires.

4. The method of constructing a thermosensitive device, which consistsin twisting two copper conductors together so that the turns of onealternate with the turns of the other, twisting a heating element aroundsaid conductors, and heatin the unit to form a layer of cop er oxideetween the two conductors and etween each conductor and the heatingelement.

5. The method of constructing a thermosensitive device, which consists.in copper plating two metallic electrodes, twisting them together sothat the turns of one alternate with the turns of the other, twisting aheating element around said electrodes, and heating the entire unit toform a layer of copper oxide between the two electrodes and between eachelectrode and the heating element.

In testimony whereof I aflix my signature.

LARS O. GRONDAHL.

